# Revision history [back]

### cannot build documentation

Hi,

I followed the steps in How to contribute but I'm not being able to build the documentation.

I tried:

sphinx-build opencv/doc/ tmp


but:

writing output... [ 0%] index
Exception occurred:
File "/usr/local/lib/python2.7/dist-packages/Sphinx-1.2.2-py2.7.egg/sphinx/environment.py", line 1093, in get_doctree
f = open(doctree_filename, 'rb')
IOError: [Errno 2] No such file or directory: u'/home/jmss/tmp/.doctrees/index.doctree'


I also tried cmake, make, make install but in the installation directory there are no HTML or PDF files.

How can I generate the HTML or PDF for testing the changes I made to modules/imgproc/doc/structural_analysis_and_shape_descriptors.rst?

Thanks.